Method of molding



Nov. 27, 1928.

S. L. ABRAHAMS METHOD OF- MOLDING Filed Feb. 11, 1927 Inventor: $amue1. L.Abr-aham$.

His Attorney Patented Nov. 27, 1928.

uNiTEo STATES PATENT OFFICE.

SAMUEL L. ABRAHAMS, OF LYNN, MASSACHU$ETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ME'IHQD OE MOLDING.

Application filed February 11, 192?. Serial No. 167,45i3.

This invention relates to a method of mold ing an insulating covering adherently to a molded material such for example as an insulating covering on commutator clamping rings made of a molded material.

When clamping rings for commutators are made of a phenol condensation product mixed with a fibrous material, they at first satisfactorily insulate from each other the end of the bars of the commutator which they engage. However, it is found that after these clamping rings are in use for a time that the heating resulting from the operation of the dynamo-electric machine causes deterioration and carbonizing of the fibrous material thereof so that they become conducting and thereby short or ground the bars of the commutator. It is the object of the invention to carry out a method of molding an in sulating covering on a molded material which is adapted to be used in molding anadherent insulating covering on a commutator clamping ring. I do this by covering a wall of a mold with an insulating material and then molding a plastic material therein so as to cause the insulating material to adhere thereto.

The invention will be more fully explained in the following description referring to the accompanying drawing, in which Fig. 1 is a perspective view of a completed commutator embodying the invention; Fig. 2 is a perspective View of the parts of the improved c0mmutator disassembled to more clearly show its construction; and Fig. 3 is a fragmentary longitudinal section of the commutator.

In the drawing I have shown a commutator, having a clamping ring made in accordance with my invention, comprising an annulus 1 formed of a plurality of commutator bars 2 which are insulated from each other as indicated at 3, as for instance, by mica. The bars 2 forming the annulus are notched at each end at 4 to receive tapering flanges 5 formed on clamping rings 6, which it is preferred to mold of a condensation product mixed with a. fibrous material. The flan es 5 have insulating coverings 7 of mica an a binding material adhering thereto. This binding material should be one which will be softened by the application of heat, so that upon heating of the commutator incident to assembling it the insulating covering will be softened and conform to any irregularity in the bars. The clamping rings 6 are formed with recesses 8' adapted to receive the flange 9 of sleeve 10 or screw ring 11 and its washer ll. In order to prevent the sleeve 10, which is preferably made of metal, shorting or grounding the bars of the commutator a cylinder 12 of insulating material is placed in side the annulus of commutator bars and extending over the insulation covering 7 as shown in Fig. 3.

It is preferred to form the clamping rings 6 of phenol condensation product mixed with- Letters Patent 1,108,329, Aug. 25, 1914, to

Callahan. However, it is not wished to limit the invention to the use of these specific materials for it is obvious that other molded and insulating materials may be substituted for those above referred to in carrying out the invention. The ring 6 is formed in accordance with my invention by applying a coating of mica mixed with a bindin material to a surface of a mold of the desired shape and the phenol condensation product in a plastic state is placed therein. In order to harden the phenol condensation product and cause the insulating material to soften and adhere thereto heat and pressure are applied to the materials in the mold. For convenience in carrying out this process a shell or cone 7 of insulating material is placed in the mold to which it conforms and the plastic material is then molded therein as above described. In using some materials it may be necessary to merely apply pressure to form the ring and cause the insulation to adhere thereto.

It is desired that it be understood that the invention is not limited to the particular process described except as defined in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. The method of molding a condensation product with a coating of insulating material including the steps of covering a wall of a mold with a mixture of mica and a binding material which is softened by the application of heat, and molding the condensation prod not in contact therewith by the action of heat and pressure so that the covering forms an inproduct in the mold, and subjecting the same sulating coating for the molded product. to heat and pressure so that the insulating 2. The method of making a commutator material adheres to the condensation product. 1 clamping ring including the steps of covering In witness whereof, I have hereuntoset my 5 a wall of a mold with a mixture of mica and hand this ninth day of February, 1927.

a binding material which is softened by the application of heat, placing a condensation SAMUEL L. ABRAHAMS. 

